


Background Shenanigans

by AnxiousPerson



Series: Their Multiverse [2]
Category: Undertale (Video Game)
Genre: Correct/Incorrect Usage of Memes, Let me know if I need to add more tags, Mostly canon to 'Their Multiverse' unless I say otherwise in a chapter, Sans of all kinds - Freeform, Swearing, crackish, this is to be read with 'Their Multiverse'
Language: English
Status: In-Progress
Published: 2021-03-06
Updated: 2021-03-06
Packaged: 2021-03-12 01:15:33
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,783
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29876877
Author URL: https://archiveofourown.org/users/AnxiousPerson/pseuds/AnxiousPerson
Summary: As the title says. These short stories are mainly to give a more in-depths of "Their Multiverse". I can try to do some requests if anyone wants one on the characters I plan to use for "Their Multiverse".
Series: Their Multiverse [2]
Series URL: https://archiveofourown.org/series/2047055
Comments: 46
Kudos: 2





	Background Shenanigans

**Author's Note:**

> The rating is for my safety when I wanna get more indulgent, but there will be no smuts! I can't do that...

Today was supposed to be a supply run day. Everyone was looking forward to it, though there was a _certain_ skeleton who was too excited to wait and almost went off on his own.

“Aw c’mon Boss! I was just gonna get some intel to be the lovely tour guide,” ~~whined~~ said Killer as he was lifted up by a black tentacle. He teasingly rubbed the appendage tightening around his rib cage. He purred, “I was gonna make it worth your while~.”

Nightmare scoffed, “I don’t care for your excuses. Every run is either done in groups or pairs. What made you think this one would be any different?” He noted with disdain that Killer was in pure bliss despite the pressure he held on him.

“Ah~. Right there. You know exactly how I like being held, _Boss_.”

Nightmare could hear the drool in his voice. And with that Nightmare immediately dropped him. Killer landed on his back- not because he couldn’t land on his feet, but because his body was like jello after being held by his boss. ~~His boss knew how to make him weak in the knees. Not that he was actively trying to.~~ Nightmare knew Killer had… strange wants and _kinks_ but he sometimes forgets those things in the heat of the moment when trying to punish him.

“Congratulations, you’re not going now.”

Killer immediately sat up in alarm. “Wait, what?”

“You heard me.”

“No, no, no. C’mon, let’s just talk this out-”

“ _Oh_ , you wanted to wash our clothes for a week? Why didn’t you just say so?” Nightmare had a no-bullshit-look in his eyes. “Please, do continue to dig yourself a deeper grave.”

Killer stood up and he clasped his hand together in a pleading motion. “Please let me go. I’ll even get on my knees.”

A tentacle pressed intently on Killer’s skull to deter him from coming closer. “You earned the right to now clean out storage room number thirty-five while Dust and Horror take care of the run today. Any more unnecessary comments will earn more rewards. That’s what you like isn’t it?”

Killer cringed as he released his hands. “Those aren’t the type of kink plays that I’m into-”

Nightmare turned away from him to head to where Horror or Dust were. “I don’t care. Get started on cleaning.”

Killer groaned once Nightmare was out of earshot. He knew Cross wouldn’t mind losing the right to go to a supply run since he preferred playing stay-at-home-guard-dog. But dammit Killer had been looking forward to playing with his knives out in new territory. He didn’t mean to leave without Cross. He just assumed Cross would know to go the moment their boss gave them the green light. How was he supposed to know the X-boy was still getting ready for it? He’s been ready since it was announced.

He wasn’t surprised when Cross found him later gathering all their clothes for washing. He expected him to show up earlier, but he wasn’t bothered at the lack of supervision. He placed down the basket of clothes as he observed the guard. Cross seemed to be in too good of a mood, which never bolded well for him, ~~or either of them for that matter~~.

“So, you _were_ severed from doing the supply run, huh.”

That made him pause. “Why does it sound like you went Criss-cross?” A new chocolate bar, that he never saw in his life, was suddenly flaunted in his vision as Cross slowly opened it to enjoy. ~~What a tease.~~

“Oh well, it’s not like _I_ did anything wrong. I don’t see why I wouldn’t be allowed to go too.” Cross munched on the bar as he spoke, “Mmm, this chocolate is actually pretty good. I should have stolen more…”

Killer tackled Cross. Cross was prepared though and stood strong, but Killer’s goal wasn’t to knock him down, it was a distraction. In that one second where Cross focused on standing firm, Killer took advantage of it and snatched the bar with his mouth. Before Cross could protest, Killer finished the bar by scarfing it down. He didn’t even bother wiping his mouth as he grinned smugly with chocolate smudges covering it.

“Wow, you’re right it _is_ good.”

Cross stared open-mouthed at his now empty hand. He thoughtlessly closed his hand and reopened it as if the bar would suddenly reappear. Red filled previously white eyelights as Cross summoned his blades. Killer was too giddy to pass on such a great treat and pulled his knife out his pocket.

The first move went to Cross who teleported behind Killer and tried to slash his back. Killer didn’t bother turning around once he heard the port, he just rolled forward to avoid the coming blow. As he was on the ground, he swiped his feet under Cross’s and tripped him. Cross cursed as he fell backward and readied his blades to block Killer’s thrust of his knife. After the exchange of blades scraping against one another, the two teleported a distance away from each other to straighten themselves before running towards one another to slice the other.

Loud clangs filled the hallway as the two traded blows after blows without caring for the environment around them. Cross had used their terrain as barriers against some of the attacks while Killer would throw them. Not a single care was given to their surroundings. A big mistake, considering this wasn’t their rooms or the training grounds.

Suddenly an axe was brought down in between them before they could clash head-on again. The two halted in their fight as they looked towards the newcomer.

“You fuckers better explain why there’s a mess outside of _my_ kitchen.” Horror’s single red light consumed his entire eye socket. He brought up his trusty axe and laid it on his shoulder while his other hand scratched the inside of his empty socket. “Don’t make me wait long.”

“Yes, don’t keep Horror waiting. I would also _love_ to hear why there’s just a trail of destruction from Dust’s room. I noticed a knocked over laundry basket and thought to follow the huge path of _debris_ littering my hallways. Care to explain?” That was Nightmare’s voice and he was furious. His tentacles were edged as they swirled haphazardly around him.

Dust was right behind Nightmare; his left eye flared dangerously as he kept his hands in his jacket’s pockets. His whole tensed posture radiated danger as he glared at the reckless two.

Cross gulped and dispersed his weapons as he quickly stood straight to attention. “Killer stole my chocolate that I nabbed on the run.” He flinched at his poor admission. Welp, they were so _dead._

“ _Oh?_ ” Not the dreaded ‘ _Oh_ ’ from Nightmare. He only started his sentence with that if he was – “You two will no longer consume any form of chocolate for a month and you will clean up your messes.” Nightmare stressed out his next words. “Normally, I would only say to replace all the broken furniture, but someone is obviously so restless to leave, they’ve become bored of their own home. To fix this,” He smiled sweetly as his eye held a storm of rage. “I think a change of rooms will help them. Don’t you agree, _Killer?”_

How is it that even without skin, Killer could feel cold sweat dripping down his forehead and back. He grinned nervously back at his boss. “I wouldn’t mind sharing rooms with the walking X-man if that’s what you’re suggesting.”

Cross wisely kept his mouth shut despite wanting to reject Killer’s words. He didn’t want any more punishments. He wasn’t Killer, the moron who was constantly seeking out a dangerous thrill, a high like no other. He just wanted chocolate… And now he was banned from it.

Nightmare glanced at Cross before his gaze flickered back to Killer. “That doesn’t seem like a bad idea. You two did make a mess after all. I guess it’s only fair that you both get to suffer together. It’s decided then. Horror, bring out _the box_.”

Horror nodded, pleased with the new outcome as he briefly left to Nightmare’s office to follow the order. The box was an ordinary looking thing, that could be held by one person, with an open slit on top for paper to be slipped into, yet it held all the locations of the multiple ~~cursed~~ special rooms in their household.

The box was shaken before Nightmare took out a piece of paper. He merely glanced at it and slid it back into the box. “You two will be living in the standing statue room until Cross can replenish my furniture.”

“Boss!” The two tried to protest.

Nightmare’s eye slitted as it narrowed. He glared down at the two. “Did you two say something?”

Cross clamped his mouth down and slammed a hand over Killer’s to keep it shut. He knew if they said anything else, their punishment would get worse.

“Good. It seems we’ve come to an agreement.” And with that Nightmare turned on his heels and faded into the shadows. He had important documents to fill out when those idiots were causing a ruckus.

Cross groaned and punched Killer’s arm, “Why’d you have to drag me into your punishment too!?”

Killer rubbed his arm and gave a punch back. “What? Can’t stand a few statues to be your roommates? There’s nothing wrong with them. I already named them all. You’ll fit right in. You’re practicing to be a guard dog, right? They can show you how stiff you need to be.”

Before Cross could land another punch, Horror slapped his hand down and scolded them, “Knock it off. Get to cleaning.” When the two looked like they were going to protest, Horror tapped the box menacingly. “ _Now._ ”

They didn’t need to be told twice as they raced to start cleaning. Horror huffed and went back into his favorite room while Dust watched the two bicker back and forth as they cleaned. Someone had to keep an eye out for Killer, when he was completing his punishments; and while usually it was Cross, Dust made for a good stand-in. Dust cursed them both as he slumped against a wall and kept watch.

“You know Nightmare didn’t say I couldn’t leave with you when you go out to collect more useless trinkets.” Killer spoke up once they finally got done cleaning their mess and Dust left them to curl up in the nearest nesting room.

“Doesn’t mean you can come with me.”

Killer draped himself completely on Cross’s back. “Aw, don’t be like that. We can have so much fun together.”

“Go fuck yourself.”

“I prefer fucking you.”

Cross made a face as he shrugged Killer off. “I wouldn’t touch you with a ten-foot pole.”

Killer winked, “For now.”

“Never.”

“Welp, I’m gonna go pack my stuff for our honeymoon. Boss is probably only gonna allow us in our rooms once, so you better get everything you need from your room.”

Cross sighed and walked off to gather his stuff. Killer did the same.

The room was already creepy enough, yet Killer still found ways to make his ~~fears~~ worries seem foolish. Currently, all the statues had googly eyes and bad make-up on their faces. All the stone statues were posed in some sort of standing poses. Killer was laying on a thick futon that was obviously stolen from a nesting room and a small pillow holding his head. Which damn that’s a good idea actually. Why didn’t Cross think of that instead of bringing a sleeping bag? Though there was no way Cross would lose face by leaving to get one as well. Killer would so hold that over him and he wasn’t going to give him that power.

Killer’s eyebrows rose when he noticed what Cross laid down on the opposite side of the room as him. “Huh, I’m surprised you didn’t nab some bedding from-”

Cross snapped, “I don’t need it. A sleeping bag is just fine.”

“Okay then, why are you so far away?” Killer patted the space next to him. “Set your home base next to mine.”

“I am not sleeping next to you.” Cross rolled his eyes and he went about fixing his spot to be more comfortable to lay in. While he didn’t have the most comfortable bedding, he did have several pillows that he laid around and under the sleeping bag.

“Aw, why not? I promise I don’t bite.” Killer paused. “Unless you want me to, of course.”

“I don’t want you to. I want to be able to sleep in peace.”

“You’re not gonna get any with that-”

ZIP. Cross wrapped himself in the sleeping bag, laid a pillow under his head, and pointedly faced away from Killer. “Good night.”

Killer chuckled, “Good night Criss-Cross.”

Cross was surprised that Killer didn’t try to engage him in more conversations. He guessed Killer might actually feel a tad bit guilty for dragging him into his punishments for once. He chanced a small glance at Killer, only to wordlessly huff and look away. Killer was carelessly covering himself with a big comforter, that had Cross silently fuming in envy, as he tapped away on his phone. The blanket barely covered half of Killer from how he laid it on himself.

The room was a bit chilly, but Cross decided he would toughen it out and not get more blankets to fight the cold. He was falling asleep but would wake up randomly due to his endless shivering and occasional need to sneeze.

Killer huffed as he noted the stubbornness that was Cross. The youngster would waken constantly to the cold and tried miserably to burrow deeper into his sleeping bag; it wasn’t working. He quietly rose from his bed and stood next to Cross. If Cross had noticed Killer’s nearness, he would have most definitely thrown a fit. Cross didn’t so much as twitch a muscle when Killer picked him up. ~~Why did that make Killer feel a bit happy that Cross trusted him so much to not hurt him as he slept?~~ What an idiot to not keep one eye opened when sleeping.

He gently set him on his bed and wrapped his comforter snuggly around Cross. Cross released a pleased sigh as he slept on. While he didn’t feel the cold much, the blanket did make him feel ~~safe~~ more comfortable. Guess he wasn’t sleeping with one since Cross had his. As he laid down next to Cross, Cross managed to wiggle his arms out of his sleeping bag and dragged Killer into his bundle of warmth. He could only freeze as Cross nuzzled his chest. If he had a heart it would be beating out of his ribcage right about now. He kept his arms to himself as Cross hugged him close under the comforter.

As time passed Killer began to feel drowsy and succumbed to the warmth.

Cross felt warm. Too warm. Yet it felt too good to leave it. He nuzzled into what he thought was one of his pillows. Well, it’s not like Nightmare had given them any jobs to do today so he could just sleep in a bit more. Ah, but maybe not too long since Horror didn’t like them missing breakfast, or any meals for that matter. The last time someone was late, Horror dragged them onto their spot at the table and kept track of their meals for next few days.

The pillow huffed and soothingly rubbed his back, which felt wonderful. When the motion stopped, Cross ~~whined~~ mumbled, “Don’t stop… That felt good…”

“Did it now? I don’t mind, but how long until-”

Cross first reaction to hearing Killer’s voice so close was to push the offending sound away. He ended up only getting Killer out of his blanket. His blanket? Wait, wasn’t that Killer’s comforter-

“I knew you would do that.” Killer laughed as he sat up on the bedding. “You never stop being so funny you know?” _Despite knowing what to expect from you, I can’t help but be amused._

“Why am I here?”

“Nightmare punished us remember-”

“Not that.” Cross held up the offending comforter like its crimes was too much warmth. “Why am I on your bed?”

“You looked cold so I thought I should warm you up.”

Cross sat up and stared at Killer. “Why would you-”

A loud knock was the only warning they got when Horror entered the room to grab them and carried them up on his shoulders like they were a sack of potatoes. “I don’t care what you two did last night. You won’t be skipping breakfast.”

“W-wait!! It’s not like that I swear!” sputtered Cross.

“Horror, Cross grabbed my no-no place~.” Killer was an ass.

“I did not!!”

Horror huffed as he walked out the room and towards their dining room, “Keep what you two do behind closed doors.”

“Come on, Horror we didn’t do much!”

“Yeah, we only just held each other _real_ close. We even ignored the five-feet rule. Can you believe that?”

“Stop!”

Horror had just brought them to the dining room when Cross covered his face with his hood and yelled that. Nightmare sat at the head of the table with Dust sitting on his left side.

Nightmare looked at the three in front of the doorway, unamused. “Do I need to know what happened?”

“No!” That was Cross. He was accidentally a bit too loud answering, so he rushed to fix his mistake. “No, it’s not that important Boss.”

Nightmare sighed and decided to let it go. He didn’t want another headache. “Horror, you can set them down now. I’m sure they can find their way to their seats without any more assistance.”

Horror didn’t hesitate to shrug them off his shoulders as he placed his arms at his side. “Okay.”

Cross landed on his face while Killer landed on his feet. Dust and Killer chuckled as they watched Cross groan on the floor. Horror’s only reaction was to not care and sit next to Dust’s left side. Killer grinned smugly and sat on Nightmare’s right side. Cross frowned; he wanted to sit there. The two were in a constant competition to sit by Nightmare’s right side while Dust and Horror came to a silent agreement on how they sat on the left side. Cross sulked as he sat on Killer’s right side.

Breakfast was a normal affair. Nightmare didn’t like them making too much of a fuss during mealtimes and Horror didn’t like them playing with their food since it could lead to waste. This was the only time Killer was on his best behavior. They did make small talk sometimes, but today was a quiet day. Nightmare seemed a bit more tired than usual and the gang didn’t want to stress him out more. They all silently and unanimously agreed to give their boss some space.

Normally after meals, Dust usually was a lot more mellow after eating and would go to the nearest nesting room and Cross would sometimes join him, but unfortunately Cross had to go out and get some furniture. Dust didn’t mind being alone, but he was a bit of a cuddly skeleton and Cross was the only one who knew of that habit. The two would often hang out in the same nesting room and just cuddle.

Cross noticed the displeased expression on Dust as they all walked out the dining room. He wanted to provide him some comfort, but he knew not to keep Nightmare waiting on his replacements. He made a promise to get a souvenir for Dust on his travels to himself.

Killer wrapped his arm around Cross’s shoulders as they walked down the hallways. “Sooo, you’re going out right? You didn’t follow Dust.”

“Yes, I’m going out, but only to replace the furniture we broke.” Cross shrugged off the arm on him. “You’re not coming.”

“Why not?”

“Because I said so.”

“Don’t tell me you’re going to choose Horror over me?” There was a bit of hurt in Killer’s voice that made Cross pause.

“I…” Cross saw the dejected look on Killer’s face. ~~He was such a pushover.~~ “Fine, let’s go together.”

Killer grinned and slapped his back. “I knew you were my best bud!”

“…You were pretending to be sad weren’t you.”

“Hey, it worked didn’t it?”

Cross sighed as he opened a portal. Killer didn’t waste any time as he entered it and Cross quickly followed suit. Killer was too unhinged to be by himself. Sometimes, Cross debated on getting a collar and a leash whenever they traveled the multiverse.

“Rule number one: do not stray too far from me, Killer.” Cross was going to set some rules down. He trusted that Killer would obey them since he was the one who could end their trip immediately. “Number two: if I call you, you have to come to me right away. Number three: yes, you can wreak havoc but only as a distraction for me to get some-”

“Crap.” Killer finished for him.

“No. Replacements for Nightmare’s collection. If I remember right, he some from this AU.”

“Urgh, why do you have to get him the same stuff? Can’t you just grab some other crap. I’m pretty sure he would love new collectibles.”

“Do you really want to increase his collection?”

“…No.”

“Alright then, I’ll start at the museum. Go be a menace as usual.” Cross barely finished speaking when Killer rushed to his nearest victim. He knew he couldn’t reign in Killer’s thirst for a good fight. He hoped the only issue he would have would be figuring out where to hold the newly acquired replacements. He started on his task of collecting the items.

Killer’s goal was to find the best opponent to fight to pass time with and they usually showed up after he killed a few weaklings. Though Killer wasn’t allowed to kill much, since Nightmare rather have live food sources of negativity, so he settled for causing as much injuries as possible to people. The only people he killed so far were a bit accidental, but how was it his fault they incorrectly dodged the way he swung his knife. He wasn’t even trying to be deadly. He didn’t have to wait long thankfully.

The Sans of this AU showed up to try to halt Killer’s rampage. They were a bit fun playing with at first. Their attacks were strong as usual, but it was too pattern ordinated which was boring. It got a bit more interesting when their Undyne joined in their fight. Killer frowned when his knife pierced Undyne’s stomach. He didn’t expect her to fall so quickly and easily. He watched as her dust scattered. Well, not much was lost. He noticed the other Sans stared wide eyed at their Undyne. They were just frozen. He figured this Sans probably never seen a death so up close.

A paint puddle was beginning to form in front of the Sans, who still wasn’t moving. Killer’s blood began to pump in excitement. It was his lucky day! He would get to fight the protector; a very fun opponent who was as unpredictable as him. He readied his knife as he raced towards the now standing skeleton looking at him with annoyance.

Ink swiped his brush in front of him and paint splattered. Killer was able to dodge the paint by teleporting and was glad to see that it held an acidic effect when whatever the liquid touched began to melt. Another challenge to overcome; getting close without getting burned. How delightful! He loved new challenges.

“Killer, we’re leaving now!” That was Cross yelling. He must have gotten everything he needed from this place.

Killer bit his lip as he debated ignoring Cross. He knew he wouldn’t get another opportunity to fight the protector one-on-one again. ~~Because he was too weak. Only Nightmare could take on the guardian.~~ Not to mention, their boss did forbid them from engaging the creator without back-up and a proper plan. Ink never went easy on his adversaries. ~~Well, maybe sometimes Error, but he could be wrong.~~ Ah, but Cross would tattle on him. Lame.

He sighed, as he turned away from Ink and ran to where he heard Cross. A mistake on his part because he didn’t see what Ink was doing. At least he was able to prepare himself for the blow. Despite having his back towards the other, Ink teleported in front of him and swung his brush straight towards his stomach.

Today might not have been a lucky day after all. Was all Killer could think as the breath was knocked out from him and he flew back several feet. He probably would have kept soaring through the air if it wasn’t for Cross slamming into his back and grabbing him. The sound of opening and closing portals was lost to his ears as Cross tried to make sure Ink wouldn’t be able to follow them.

Cross finally stopped changing locations after he felt safe enough to just go straight home. He would have gone straight to where he had all the stolen items, but he settled for warping straight to their new room. Killer still wasn’t able to function properly and was held up in Cross’s arm like a doll.

When Killer came to, his head was resting on Cross’s lap as Cross mindlessly patted his head. They were both situated on Killer’s futon. Cross was staring worryingly at Killer. He was waiting for Killer to get his bearings. ~~How sweet.~~

The moment Cross realized Killer was awake, he scolded him, “You are a fucking idiot. You should have come the moment I called you. You lost completely to one swung from Ink. Was it worth it?”

Killer grinned smugly. “Yeah, since I’m getting the best treatment that is your lap.”

Cross scoffed, “Fuck off. You’re lucky I’m even doing this.” He didn’t stop patting Killer’s skull. Killer didn’t say anything. ~~He didn’t want it to stop.~~

The sound of their door opening got their attention. Cross tried to move to stand once he realized it was Nightmare walking towards them. Unfortunately, Killer’s body wasn’t cooperating with his thoughts, so he ended up rolling off Cross’s lap when he stood up. Cross looked down at him in shock.

To save face, Killer attempted to pose as a French girl on his spot on the floor. “Yo, what’s up Boss?”

“You left.” Was all Nightmare said as he glared down at Killer.

“Yeah, how else would I be able to eat? Didn’t you watch Horror drag us-”

“You left this realm. You were not given permission to leave Killer.” Nightmare was mad. He glared at Cross next. “Why did you let him out?”

Cross gulped and looked guilty down at the ground, just so he didn’t see the ~~disappointment~~ harsh stare from his superior. “He was feeling restless. We weren’t gone long-”

Nightmare wrapped a tentacle around Killer’s stomach and lifted him up. Killer winced in pain which didn’t go unnoticed by the other two. “…He’s hurt. How?”

Cross kept his mouth shut. He knew if he told the truth, they would get into serious trouble.

“I tried to fight Ink.” Killer knew better than lying and he wasn’t going to let Cross get into more trouble for his dumb mistake.

Nightmare pinched his forehead. “Why must you be like this… You’re going to the infirmary and we’ll get your injuries checked out. You will tell me everything you did.” He began to walk back out the room. He stopped a bit before the doorway. “Cross.”

“Yes sir.” Cross stood a bit straighter.

“You can take a break for the remainder of today. I saw that you gathered some of my materials. I do expect them to be fixed into their places tomorrow.” Nightmare left after saying those words.

The tension in Cross went away after he didn’t feel Nightmare close by. He sat on the futon as he tried to collect himself. He was so scared when he saw Killer go flying, and he was sure that’s what alerted their Boss something was amiss when they returned. He finally noticed something after he calmed down. All the stone statues were now facing where Killer’s bed was, and they all were in different spots. Their make-up somehow was even more prominent, and all the googly eyes were looking towards his direction. He shuddered and decided that he would go give Dust that souvenir he promised (even though he made it to himself). ~~He didn’t want to be alone in the statue room.~~ He felt it was time for some cuddles anyways.

**Author's Note:**

> Honestly, I couldn't think of an AU for them to go to so just imagine whatever! I tried to keep it vague so that would make it easier... I'm sorry I cannot write fight scenes for the life of me. Also, this takes place between chapter three and four from "Their Multiverse".  
> Haha, I wonder if I'm obvious on what pairs I want...  
> Uh, I hope you like this BookwyrmFinallyGotAnAccount! They were a major inspiration for me to write this! So thank you!  
> Minor note: It's like 4am. Why am I alive right now....


End file.
